John 17:2 says, "You have given him (Jesus) authority over all flesh."
This is not talking about the original power given to Jesus over all things. Instead, this verse refers to His power as our Mediator. He rules souls with a scepter of righteousness, either pardoning them if they believe or judging them if they don't.
The verse goes on to say Jesus has authority "to give eternal life."
It's not something we can earn. There is no merit in our good works. The only way anyone is saved is through the grace of God. Salvation is a gift.
Just who can receive this gift?
As we continue to read John 17:2, we see the answer: "all whom you (the Father) have given him (Jesus)."
This is the same language used in John 6:37 and 39: "All that the Father gives Me will come to Me, and the one who comes to Me I will certainly not cast out ... This is the will of Him who sent Me, that of all that He has given Me I lose nothing, but raise it up on the last day."
All refers to everyone who will believe. Only those the Father has given to the Son are able to respond to the gospel.
We struggle with this, but the promise in this verse is incredible. Every single person the Lord gives the Son will receive eternal life—though not one of us deserves to be saved. God exercises His sovereign will in saving us.
It's natural for us to want to be in control. In fact, there are many people who believe if the Lord chooses us despite our choices, not because of them, He has negated our free will.
Do we actually have free will? Yes. But that free will is restricted by the laws of nature. We can choose to walk across a bridge, but we can't choose to flap our arms and fly across the bridge.
In the same way, we can't choose to make ourselves righteous, thereby, earning salvation. We are born with a sin nature that makes it impossible.
Romans 3:23 says, "All have sinned and fall short of the glory of God."
It is only through the grace and power of God that free will truly becomes free in the sense of being able to choose salvation (John 15:16). It is the Holy Spirit who works in and through a person's will to regenerate that person (John 1:12-13) and give them a new nature "created to be like God in true righteousness and holiness" (Ephesians 4:24). Salvation is God's sovereign work. At the same time, our motives, desires, and actions are voluntary, and we are rightly held responsible for them. 
Let's read verses 1 and 3 of John 17: "When Jesus had spoken these words, he lifted up his eyes to heaven, and said, 'Father, the hour has come; glorify your Son that the Son may glorify you … And this is eternal life, that they know you, the only true God, and Jesus Christ whom you have sent."
The essence of eternal life is knowing the only true and living God. The only way we can know Him is by knowing Jesus. We get to know the true and living God and His Son Jesus Christ—throughout eternity. That journey begins the moment we believe in Christ as our Lord and Savior. And that relationship grows deeper and deeper—forever.
Our Lord submitted to the Father's sovereign will because He recognized the need for the cross. How could Jesus submit to His Father knowing He would be beaten, spit upon, flogged, and crucified? Prayer.
But if He knew all this ahead of time, why pray?
Prayer isn't about conveying information; it's about fellowship. We don't pray because God needs to be reminded of our needs. But still, He calls us to seek His will, to request His intervention in our situation, to fellowship with Him.
Daniel read the prophet Jeremiah's words and realized the people of Israel were nearing the end of their 70 years in captivity. Did he simply say, "Awesome!" and sit back and wait for things to unfold? Definitely not!
Daniel 9:3 says, "So I gave my attention to the Lord God to seek Him by prayer and supplications, with fasting, sackcloth and ashes."
And then Daniel goes on to pray that God would do what He had promised to do.
Just because God is sovereign … Just because He has ordained things to take place … This doesn't mean we're to sit back and do nothing. Instead, we're to pray for the Lord's will to be done.
In Matthew 6:9, Jesus taught us to pray. What we refer to as the Lord's Prayer begins like this: "Our Father in heaven, hallowed be your name. Your kingdom come, your will be done, on earth as it is in heaven."
We may not know what the future holds. We may not know what God's plan is. We may not know what God's will is. So, we're to pray, submitting ourselves to the authority of Christ, and living in obedience to His Word.